HCMV/HSV fusion glycoproteins

ABSTRACT

A fusion protein comprising a portion of a glycoprotein of HCMV fused to a portion of a glycoprotein of HSV is described.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to GB 9409962.9filed May 18, 1994.

The present invention relates to recombinant cytomegalovirus proteins,more particularly to fusion proteins comprising a portion of a humancytomegalovirus (HCMV) protein and a portion of a protein from herpessimplex virus (HSV) and their expression in eukaryotic cells. Theinvention further relates to methods of constructing and expressing thesaid fusion proteins, intermediates for use therein and recombinantproteins which may be obtained from the intermediates. Recombinantproteins of the invention have potential utility in the development ofvaccines for the prevention of HCMV infection and/or HSV infection.

HCMV is human DNA virus belonging to the family of herpes viruses. Incommon with other herpetic viruses (such as Herpes Simplex Virus (HSV)Varicella Zoster Virus (VZV)) HCMV is made up of a DNA core, an outercapsid and covered by a lipid membrane which incorporates virus specificglycoproteins.

Human cytomegalavirus is endemic in most parts of the world. Primaryinfection however normally results in subclinical disease after whichthe virus becomes latent retaining the capacity to reactivate at anytime. Among two populations, HCMV is however responsible for seriousmedical conditions. HCMV is a major cause of congenital defects in newborns. Also associated with infection in such infants, are hearing loss,and poor intellectual performance. The second population at risk areimmunocompromised patients such as those suffering from HIV infectionand those patients undergoing transplantations. In this situation thevirus becomes an opportunistic pathogen and causes severe disease withhigh morbidity and mortality. The clinical disease causes a variety ofsymptoms including fever, hepatitis, pneumonitis, and infectiousmononucleosis.

This therefore explains the extensive efforts of those skilled in theart and the importance of studies dedicated to the biology of theseviruses. However no efficient vaccine against HCMV is currentlyavailable.

Therefore there still exists a need for antigens which will effectivelyprotect against challenge with the HCMV virus.

According to a first aspect of the present invention there is provided afusion protein or an immunogenic derivative thereof comprising a portionof an HCMV glycoprotein fused to a portion of a glycoprotein of HSV.

By a portion of an HCMV glycoprotein is meant a part of the proteinwhich contains at least one antigenic determinant capable of raising animmune response specific to HCMV. A preferred HCMV glycoprotein is gB.

By a portion of a glycoprotein of HSV is meant a part of the proteinwhich contains at least the signal sequence of the glycoprotein andoptionally additional parts of the protein which contain at least oneantigenic determinant capable of raising an immune response specific toHSV and/or contain a sequence enhancing the secretion of the proteinwhen suitably expressed. A preferred HSV glycoprotein is gD, inparticular HSV type 2gD.

The gB protein of HCMV strain AD 169 contains 906 amino acid residues:amino acids 1 to 24 correspond to the signal peptide and residues 712 to776 the membrane anchor domain. The molecule presents 19 potential sitesfor glycosylation. Used alone for immunization, the gB protein generatesan immune response which is insufficient to coffer protection against achallenge with the virus.

The protein gD from herpes simplex virus (HSV) is composed of 394 aminoacids: its membrane anchor domain occurs in the C-terminal end of themolecule, between amino acid residues 339 and 365.

Preferably the fusion is between an amino acid in the N-terminal part ofa portion of the HCMV gB protein and an amino acid at the C terminus ofa portion of the HSV gD protein.

Preferably both the HCMV gB protein and the HSV gD protein components ofthe fusion protein of the invention lack a membrane anchor domain.

Preferably the portion of the HCMV gB protein comprises a non-cleaveableform of HCMV gB. Suitably this is achieved by changing one or more aminoacids at a cleavage site of the protein. Preferably this is byexchanging Arg 458 and Arg 459 for Glu and Thr respectively. Such anon-cleaveable form of gB is novel and forms a further aspect of theinvention. One advantage of having a non-cleaveable form of gB is thatthere is a greater secretion of the protein when suitably expressed.

Suitably the portion of the HSV protein comprises the signal sequence ofgD2 and optionally amino acids 26 to 52 of gD2 and/or the sequence fromgD2 which is PEDSALLEDPED or functionally equivalent derivatives thereofwhich are slightly shorter or longer.

Preferably the portion of gD includes amino acids from the signalportion of gD2 (amino acids 1 to 25) and the amino acids residues 26-52of HSV2 gD.

In one specific embodiment there is provided a fusion protein comprisingamino acid residues 1-52 of the HSV gD protein fused to residues 28-686of the HCMV gB protein (herein designated HCMV gB 685*).

Preferably further sequences from HSV gD can be added to the fusionprotein, in particular at the C terminus of the HCMV gB protein.

In a further preferred embodiment the amino acid sequence PEDSALLEDPEDwhich is derived from an internal gD2 sequence is included at the Cterminal end of the protein HCMV gB 685* to produce the protein hereindesignated HCMV gB 685**. This amino acid sequence improves thesecretion of the fusion protein when suitably expressed.

The proteins HCMV gB 685* and HCMV gB 685** in particular have beenfound to be useful for developing an HCMV vaccine.

Further preferred fusion proteins are as defined in the claims.

The fusion proteins of the present invention are immunogenic. The termimmunogenic derivative as used herein encompasses any molecule which isa fusion protein which is immunologically reactive with antibodiesraised to the fusion protein of the present invention or parts thereofor with antibodies recognising the HCMV gB protein, the HSV gD protein,the HCMV virus or the HSV virus, or which elicits antibodies recognizingthe fusion protein, the HCMV gB protein, the HSV gD protein, the HCMVvirus or the HSV virus. In particular immunogenic derivatives which areslightly longer or shorter than the fusion protein of the presentinvention may be used. Such derivatives may, for example, be prepared bysubstitution, addition, or rearrangement of amino acids or by chemicalmodifications thereof including those for enabling coupling of thefusion protein to other carrier proteins such as tetanus toxoid orHepatitis B surface antigen. All such substitutions and modificationsare generally well known to those skilled in the art of peptidechemistry.

Immunogenic fragments of the fusion protein which may be useful in thepreparation of vaccines may be prepared by expression of the appropriategene fragments or by peptide synthesis, for example using the Merrifieldsynthesis (The Peptides, Vol 2., Academic Press, New York, p3).

In a further aspect of the invention there is provided recombinant DNAencoding the fusion protein of the invention. The recombinant DNA of theinvention may form part of a vector, for example a plasmid, especiallyan expression plasmid from which the fusion protein may be expressed.Such vectors also form part of the invention, as do host cells intowhich the vectors have been introduced.

In order to construct the DNA encoding a fusion protein according to theinvention, cDNA containing the complete coding sequences of the HCMV gBand HSV gD proteins may be manipulated using standard techniques see forexample Maniatis T. et al Molecular Cloning, Cold Spring HarborLaboratory, Cold Spring Harbor N.Y. (1982)! as further describedhereinbelow.

In the course of carrying out the techniques described above recombinantDNA encoding fragments of the HCMV gB and HSV gD proteins may beobtained which further forms part of the present invention.

In particular DNA segments encoding a non-cleaveable form of HCMV gB,the truncated protein HCMV gB (gB lacking the membrane anchor domain)and the truncated protein HSV gD (gD lacking the 5' membrane anchordomain) are important intermediates.

Vectors comprising such DNA, hosts transformed thereby and the truncatedor hybrid proteins themselves, expressed as described hereinbelow allform part of the invention.

For expression of the proteins of the invention, plasmids may beconstructed which are suitable either for transfer into vaccinia virusor transfection into Chinese Hamster Ovary (CHO) cells or Vero cells.Suitable expression vectors are described hereinbelow.

For expression in vaccinia a vaccinia transfer plasmid such as pULB 5213which is a derivative of pSC11 (Chakrabati et al. Molecular and CellularBiology 5, 3403-3409, 1985) may be used. In one aspect the protein maybe expressed under the control of the vaccinia P₇.5 promoter.

For expression in CHO-K1 cells a glutamine synthetase (GS) vector suchas pEE14 may suitably be used so that the protein is expressed under thecontrol of the major immediate early promoter of human cytomegalovirus(hCMV-MIE). Alternatively a vector which allows the expression of thecoding module as a polycistronic transcript with the neo selection genemay suitably be used. In one preferred aspect the coding module is underthe control of the Rous Sarcoma Long Terminal Repeat (LTR) promoter.

Preferably the plasmid for expression in CHO-K1 cells carries a GSexpression cassette suitable for gene amplification using methioninesulphoximine (MSX). Alternatively the plasmid for expression in CHO-K1cells carries a DHFR expression cassette suitable for gene amplificationusing methotrexate (MTX).

Preferably expression of the fusion proteins of the present invention iscarried out in the presence of sodium butyrate and/or dimethylsulphoxide (DMSO) which have been found to enhance gene expression.

In yet another aspect of the invention there is provided a vaccinecomposition comprising a fusion protein according to the invention incombination with a pharmaceutically acceptable carrier, a proteinaccording to the invention for use in vaccinating a host and the use ofa protein according to the invention in the preparation of a vaccine.

It is known that amino acids 1-23 of mature gD can elicit in animals aprotective and neutralising response against a lethal challenge,moreover this peptide when appropriately formulated can elicit a CTLresponse (Watari et al, reference in Example 2 below).

Accordingly the fusion proteins of the present invention which containthis peptide not only offer a protective response for HCMV infection butalso offer a protective response for HSV infection thereby providing anovel bi-functional vaccine.

Optionally, and advantageously, the vaccine of the present invention iscombined with other immunogens to afford a polyvalent vaccine. In aparticularly preferred embodiment the fusion protein is combined withother subcomponents of HSV e.g. gD.

In a particular aspect the invention further provides a vaccinecomposition comprising a protein according to the invention togetherwith a suitable carrier or adjuvant.

Vaccine preparation is generally described in New Trends andDevelopments in Vaccines, edited by Voller et al, University Park Press,Baltimore, Md. U.S.A., 1978. Encapsulation within liposomes isdescribed, for example by Fullerton, U.S. Pat. No. 4,235,877.

In the vaccine of the present invention, an aqueous solution of theprotein(s) can be used directly. Alternatively, the protein, with orwithout prior lyophilisation, can be mixed, absorbed or adsorbed withany of the various known adjuvants. Such adjuvants include, but are notlimited to, aluminium hydroxide, muramyl dipeptide and saponins such asQuil A. Particularly preferred adjuvants are MPL (monophosphoryl lipidA) and 3D-MPL (3 deacylated monophosphoryl lipid A) U.S. Pat. No.4,912,094!. A further preferred adjuvant is known as QS21 which can beobtained by the method disclosed in U.S. Pat. No. 5,057,540. Use of3D-MPL is described by Ribi et al. in Microbiology (1986) Levie et al.(eds) Amer. Soc. Microbiol.Wash. D.C., 9-13. Use of Quil A is disclosedby Dalsgaard et al., (1977), Acta Vet Scand, 18, 349. Use of combined3D-MPL and QS21 is described in WO 94/00153 (SmithKline BeechamBiologicals s.a).

As a further exemplary alternative, the proteins can be encapsulatedwithin microparticles such as liposomes or associated with oil-in-wateremulsions. Encapsulation within liposomes is described by Fullerton inU.S. Pat. No. 4,235,877. In yet another exemplary alternative, theproteins can be conjugated to an immunostimulating macromolecule, suchas killed Bordetella or a tetanus toxoid. Conjugation of proteins tomacromolecules is disclosed, for example by Likhite in U.S. Pat. No.4,372,945 and Armor et al. in U.S. Pat. No. 4,474,757.

The amount of the protein of the present invention present in eachvaccine dose is selected as an mount which induces an immunoprotectiveresponse without significant, adverse side effects in typical vaccines.Such amount will vary depending upon which specific immunogen isemployed and whether or not the vaccine is adjuvanted. Generally, it isexpected that each dose will comprise 1-1000 μg of protein, preferably1-200 μg. An optimal amount for a particular vaccine can be ascertainedby standard studies involving observation of antibody titres and otherresponses in subjects.

In order to define the invention more clearly reference is made to theappended drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the construction scheme for chimeric gB.

FIG. 2 shows a plasmid map of pEE14-gB685**.

The invention will now be illustrated by reference to the followingexamples.

EXAMPLE 1 Construction of Chimeric gB Molecules

The following construction steps were performed in order to cream thedifferent gD/gB fusion molecules (chimeric gB₆₈₅ * and chimeric gB₆₈₅**), see FIG. 1.

a) gB₆₈₅ NC (non cleavable)

To generate pUCI2-gB685, the gB gene of strain AD169 HCMV was subclonedfrom the genomic Hind III F fragment as an Ecl 1 fragment into the Sma 1site of pUC12 (Yanisch-Perron, C et al 1985 GENE 33, 103). A stopcodonand BamHI site was inserted into the internal EcoR1 site (position 2208of AD 169 gB) generating a truncation at aminoacid 685 (ie lacking thetransmembrane anchor aminoacids 712-776!). The HCMV gB sequence is knownfrom Cranage et al Embo J. 1986, 5,3057-3063.

In order to obtain more secretion of truncated gB₆₈₅ antigen into thecell culture supernatant of CHO-K1 cells we introduced first in thepreviously cloned and truncated gB₆₈₅ plasmid construct, pUC12-gB₆₈₅(pM7) also named pRIT14224, a double mutation rendering the gB cleavagesite at 459/460 (AD169 strain) non-cleavable. This was accomplished byexchanging (PCR) Arg458 and Arg459 for Glutamine and Threoninerespectively. More specifically the gB₆₈₅ NC (non cleavable) plasmidconstruct was generated by recombinant PCR (RPCR) according to a methoddescribed in ref. 1. Therefore two DNA plasmid preparations ofpUC12-gB₆₈₅ were digested respectively by HindIII and XmnI. Bothlinearised plasmids were separately amplified by PCR (Ampli Taq) usingrespectively primer couples Dir 268, Dir 269 and Dir 270, Dir 271. Theamplified products, about 10 ng of each PCR reaction were mixed togetherand competent E. coli HB101 cells were transformed.

Thanks to the created homologous ends (respectively 75 nct for thepUC-region and 13 nct for the mutated gB region) the linear PCR productscan undergo circularisation by recombination in vivo. About 30% of theobtained clones (0,15% efficiency) were without errors after sequencingthe whole gB region. One E. coli clone pUC12-gB₆₈₅ NC also namedpRIT14225 was chosen and DNA was prepared. A BamHI fragment of 2200 bpcontaining the gB₆₈₅ NC cassette was gel purified and ligated into theexpression vector pEE14 cut by BclI. The resulting recombinant plasmidis pEE14 gB₆₈₅ NC as named pRIT14226 or pC2 (see FIG. 1b).

(1) Jones D. H. and S. C. Winistorfer 1992 Biotechniques 12:528-533.

b) gD/gB fusion protein (chimeric gB₆₈₅ *)

Construct gB₆₈₅ * was created as follows (see FIG. 1c). The 5' leadersequence (86 bp) and signal sequence (aa1 to 25) of glycoprotein gD ofHSV2 and the mature sequence of gD from aminoacids 26 to 52 was fused toaminoacid 28 of mature HCMV gB (minus 3 aminoacids). The constructionsteps were as follows: an EcoRI-PvulI (240 bp) gD2 fragment derived fromplasmid pEE14-gD2t 1A also named pRIT13832 was ligated to a 1980 bpScaI/BamHI fragment from pUC12-gB₆₈₅ in the presence of the pEE14 vectorout by EcoRI/BclI. This resulted in pEE14-gB₆₈₅ * also named pRIT14227or pC3. The obtained chimeric gB expression cassette was verified byautomated DNA sequencing.

Plasmid pEE14-gD2t 1A contains a truncated gD coding sequence (HSV2strain G) from aminoacids 1→309 in a CHOK1 vector pEE14 (ref. 3) underthe control of the major immediate early promoter of humancytomegalovirus (hCMV-MIE). The HSV2 gD sequence is known from Lasky etal, DNA, 1984, 3, 23-29.

c) Chimeric gB₆₈₅ **

The gB₆₈₅ ** construct (see FIG. 1d) was created by adding at the C-endof the above mentioned chimeric gB₆₈₅ * expression module, an extensionof 12 aminoacids (PEDSALLEDPED) derived from an internally gD2 sequence(i.e. same truncated C-end of gD2t molecule which happens to be verywell secreted in CHO-K1 cells). More particularly the followingconstruction steps were performed. A 2002 bp long HindIII/BglII fragmentfrom pEE14.gB₆₈₅ * (pRIT14227) was ligated with a 285 bp BglIII/XbaIfragment (generated by PCR using primers Dir 287 and Dir 288 onpUC12-gB₆₈₅ NC) together with vector pEE14 cut by HindIII/XbaI. Theresulting plasmid is pEE14-gB₆₈₅ ** also named pRIT14229 or pC4 (seeFIG. 2). After sequencing the 3' end of the gB₆₈₅ ** cassette of 10clones, clone #30 was chosen and DNA was prepared by CsCl gradientpurification.

EXAMPLE 2 Expression in Eukaryotic Cells

a) Expression in CHO cells

CHO-K1 cells were transfected classically by the Ca-phosphate methodusing respectively 20 μg DNA of the following expression plasmids,pEE14-gB₆₈₅ NC, pEE14-gB₆₈₅ * and pEE14-gB₆₈₅ **. Selection of stabletransformant clones was done in GMEM medium, 10% dialysed FBS lackingglutamine (see ref. 3). The selection method for glutamine synthetasegene expression of pEE14 vector (Celltech) relies on the ability of thetransfected plasmid DNA to confer resistance to a low level ofmethionine sulfoximine (MSX). CHO-K1 clones were isolated by cloningcylinders (±26 clones respectively for gB₆₈₅ NC and gB₆₈₅ * construct).CHO-K1 gB₆₈₅ ** transfectant clones were selected/isolated using adifferent protocol. After transfection (Ca-phosphate) of about 1,4 & 10⁶cells in F80 cm² T-flask, the cells were distributed into 4×96 wellplates and each well was seeded with ±3500 cells. After selection forabout 2-3 weeks a total of 25 clones was obtained. Six clones werefurther amplified in F25 cm² and tested by Western blot analysis usingα-gD (mAb 4846) antibody and tested also by gB-specific Elisa(1F10G2/LCT62). Five out of six clones secreted high levels of chimericgB₆₈₅ ** protein into the culture supernatant of CHO-K1 cells.

These CHO-K1 clones were amplified and cell vials were made. ClonepC4204.20 was chosen for further characterisation. Expression level ofgB₆₈₅ ** antigen secreted into culture supernatant was estimated at 3-4μg/ml/5.10⁵ cells by Western blot (mAb 4846) analysis using purifiedgD2t as reference.

Table I shows the results of the expression characterisation studiesperformed by radioimmunoprecipitationassay (RIPA) on CHO-K1 cellsexpressing respectively gB₆₈₅, gB₆₈₅ NC, gB₆₈₅ * and gB₆₈₅ ** antigens.Cell extracts and culture supernatants were immunoprecipitated using apanel of different monoclonal antibodies (W. Britt) directed against gBHCMV (one sequential mAb 27-156 and two conformational mAb's 27-39 andmAb 9-3) and a neutralising human α-CMV serum (#243) and by a sequentialmonoclonal antibody (mAb 4846) directed against the NH2-part (aa12 to23) of HSV2 gD.

Table II shows the Western blot results using the same monoclonalantibodies and human α-CMV serum (#243). Above results suggest that thechimeric gB₆₈₅ ** antigen display an enhanced secretion capacity withrespect to the previously analysed gB₆₈₅ antigen derived from CHO-K1gB₆₈₅ (clone 44). The above results suggest also that gB₆₈₅ *, gB₆₈₅ **and also gB₆₈₅ NC--but not or to a much lesser degree gB₆₈₅ --aresecreted and are found in a conformational state, well recognised byconformational antibodies and human neutralising CMV serum (#243). Thechimeric gB₆₈₅ ** and gB₆₈₅ NC expressed antigen may have a conformationthat closely resembles that of native gB and may thus be extremelyuseful for development of a HCMV vaccine. It might be encouraged also touse the chimeric gB₆₈₅ ** immunogen as a component of a HSV gD vaccine.This because it was shown by Watari et al. 1987 (2) (and referencestherein) that aa1 to 23 of mature gD2 contains a CTL epitope and couldelicit a neutralising and protective immune response in mice model.

Although not a preferred embodiment of this invention, the use of thesechimeric gB₆₈₅ * one gB₆₈₅ ** antigens could facilitateisolation/purification via "gD-tag" by immunoaffinity chromatography (aswas recently shown by us).

It should be noticed that all expressed non cleavable CHO-K1 gB₆₈₅constructs in spite of the presence of the mutated 458/459aminoacids--display a (small) protein band at 33-35 kD (resembling tothe gp33 part of gB₆₈₅ cleavable). This band is recognised in cellextracts by WB analysis using mAb 27-156 (α-gp33). This finding suggestsstrongly that an alternative nearby cleavage site is activated in thesenon cleavable recombinant gB₆₈₅ constructs.

It should also be stressed that we have found a non-described (yet)processing event i.e. processing site in the NH2-part of the gB molecule(gp92-116). The detection was made possible due to the added gD-tag atthe aminoterminal part of the gB₆₈₅ module. A 34-36 kD band was detectedin cell extracts by WB analysis using α-gD monoclonal antibody mAb4846.A 69-70 kD protein fragment most likely corresponding to the carboxyhalf of the gp92-116 part of gB was detected only by RIPA using gBspecific mAbs (suggesting co-precipitation with gp33-part). this same69-70 kD band was also recognised by human neutralising anti CMV serum#243 in RIPA (see also table I). This 69-70 kD band has been detected inretrospect in all CHO-K1 gB constructs (cleavable or not). This cleavageof the aminoterminal part of gB (gp92-116) might be of biologicalrelevance (fusion) and this finding might be important for vaccinedevelopment.

(2) J. Exp. Med. 1987, 165:459-470.

(3) Cockett. M. I. Bebbington, C. R. and Yarranton, G. T. 1990Biotechnology 8 662-667.

EXAMPLE 4 Enhancing gB Gene Expression with Sodium Butyrate or DMSO

Sodium buyrate (Na But) was added at different concentration (0,5 mM, 1mM, 2 mM, 3 mM, 4 mM, 5 mM, 10 mM) to cultures of CHOK1 gB** subclones.A clear effect was observed (WB-analysis, mAb 4846) starting from 0.5 mMNaBut on, with maximum expression levels achieved at 2 mM-4 mM NaBut. Athigher (5 mM) concentration (more expression per cell is observed) thecytostatic effect of NaBut is too pronounced and therefore the totalyield of gB** is not much increased versus 2 mM NaBut treatment. Typicalresults for a subclone of gB** were about 16 fold enhancement of basalgene expression of gB** (WB-analysis) when 2 mM NaBut was added and whengB** was accumulated during 4 days. With DMSO added at 2% an 8-12 foldincrease was observed.

                                      TABLE I                                     __________________________________________________________________________    Summary of the Radioimmunoprecipitation (RIPA) results on                     different CHO-K1 cell lines expressing different                              recombinant gB.sub.685 antigens. Cell lysates were made                       in RIPA-buffer and cell culture supernatants (SN) were analysed               with a panel of different monoclonal antibodies directed against              gB and a neutralizing human α-CMV serum #243.                                                           hu CMV                                                                        serum #                                               mAb27.156                                                                           mAb27.39                                                                            mAb9.3                                                                              mAb48.46                                                                            243                                           __________________________________________________________________________    gB685 Cells:                                                                  110kD   +     +     +     -     +                                             82kD    ±  ±  ±  -     ±                                          69-70kD +++   +++   ++++  -     +++                                           33-35kD +++   +++   ++++  -     +++                                           SN: 120-125kD                                                                         +     +     -     -     ±                                          gB685NC Cells:                                                                110kD   ++    ++    +++   -     ++(+)                                         69-70kD +     +     ++    -     ++                                            33-35kD +     +     ++    -     ++                                            SN: 120-125kD                                                                         +++   ++++  ++++  -     ++++                                          gB685* Cells:                                                                 115kD   +     -     +     +     +                                             69-70kD +     +     +     -     +                                             33-35kD +     +     +     +     +                                             SN: 130kD                                                                             +     +     +     +     ±                                          gB685** Cells:                                                                125kD   ++++  +++   +++   +++   +++                                           69-70kD +++   ++    +++   -     ++                                            34-36kD +++   ++    +++   -     ++                                            SN: 130kD                                                                             +++   ++(+) ±  ++++  +++                                           __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    Summary of the Western blot analyses performed with a panel of                different monoclonal antibodies against gB and a neutralizing human           α-CMV serum #243.                                                                                       hu CMV                                                                  mAb48.4                                                                             serum #                                               mAb27.156                                                                           mAb27.39                                                                            mAb9.3                                                                              6     243                                           __________________________________________________________________________    gB685 Cells:                                                                  110kD   ++    -     ++    -     ±                                          30-33kD ++    -     +++   -     -                                             SN: 120kD                                                                             -     -     -     -     -                                             gB685NC Cells:                                                                110-115kD                                                                             +++   -     +++   -     +                                             30-33kD ++    -     +++   -     -                                             SN: 125kD                                                                             ++    -     ±  -     -                                             gB685* Cells:                                                                 120kD   +     -     ±  ++++  -                                             30-33kD ±  -     +     -     -                                             SN: 130kD                                                                             ±  -     ±  +++   -                                             gB685** Cells:                                                                125kD   ++    -     ++    ++++  -                                             33-34kD ±  -     ++    ++++  -                                             SN: 130kD                                                                             +     -     ±  ++++  -                                             __________________________________________________________________________

                  TABLE III                                                       ______________________________________                                        Primer oligonucleotides and PCR conditions used to generate the               different chimeric gB.sub.685 constructs                                      ______________________________________                                        gB.sub.685 NC(non-cleavable)   A)                                             Dir 268:5' GGACCCAAACAAGTACGAGTG                                              Dir 269:5' CGCTGGTGAAAGTAAAAGATGC                                             Dir 270:5' GTACTTGTTTGGGTCCTATG                                               Dir 271:5' CCGCTGTTGAGATCCAGTTCG                                              PCR reaction conditions:                                                      on 0,5 μg HindIII or XmnI lineraised pUC12-gB.sub.685                        25 cycles: 2 min 90° C., 2 min 55° C., 2 min 72°       C.                                                                               1 cycle: 2 min 94° C., 2 min 55° C., 15 min 72°       C.                                                                            with primer couples Dir 268, Dir 269                                          and separately with primer couples Dir 270, Dir 271                           Chimeric gB.sub.685 **         B)                                             Dir 287:5' GCCTCAAGATCTTCATCGCCGGGAACTCG 3'                                    ##STR1##                                                                      ##STR2##                                                                     ______________________________________                                    

    __________________________________________________________________________    SEQUENCE LISTING                                                              (1) GENERAL INFORMATION:                                                      (iii) NUMBER OF SEQUENCES: 7                                                  (2) INFORMATION FOR SEQ ID NO: 1:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 21 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD169                                                             (C) INDIVIDUAL ISOLATE: Dir 268                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1:                                      GGACCCAAACAAGTACGAGTG21                                                       (2) INFORMATION FOR SEQ ID NO: 2:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 22 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir 269                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2:                                      CGCTGGTGAAAGTAAAAGATGC22                                                      (2) INFORMATION FOR SEQ ID NO: 3:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 20 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir270                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 3:                                      GTACTTGTTTGGGTCCTATG20                                                        (2) INFORMATION FOR SEQ ID NO: 4:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 21 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir 271                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4:                                      CCGCTGTTGAGATCCAGTTCG21                                                       (2) INFORMATION FOR SEQ ID NO: 5:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 29 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir 287                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 5:                                      GCCTCAAGATCTTCATCGCCGGGAACTCG29                                               (2) INFORMATION FOR SEQ ID NO: 6:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 58 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: DNA (genomic)                                             (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir 288                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 6:                                      TAGCTCTAGATTAATCCTCGGGATCCTCTAAGAGGGCCGAGTCCTCGGGGGAATTCGC58                  (2) INFORMATION FOR SEQ ID NO: 7:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 12 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: peptide                                                   (iii) HYPOTHETICAL: NO                                                        (iv) ANTI-SENSE: NO                                                           (v) FRAGMENT TYPE: internal                                                   (vi) ORIGINAL SOURCE:                                                         (A) ORGANISM: Human cytomegalovirus                                           (B) STRAIN: AD 169                                                            (C) INDIVIDUAL ISOLATE: Dir 288                                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 7:                                      AspGluProAspGluLeuLeuAlaSerAspGluPro                                          1510                                                                          __________________________________________________________________________

What is claimed is:
 1. An isolated fusion protein comprising a HumanCytomegalovirus glycoprotein B (HCMV gB) fused at its amino terminus tothe carboxy terminus of a portion of Herpes simplex virus type 2glycoprotein D (HSV2 gD), wherein the HCMV gB consists of amino acids28-686 of the gB of HCMV strain AD 169 wherein arginine 458 and arginine459 are replaced by glutamine and threonine, respectively, and theportion of HSV2 gD consists of amino acids 1-52.
 2. An isolated fusionprotein comprising a Human Cytomegalovirus glycoprotein B (HCMV gB)fused at its amino terminus to the carboxy terminus of a portion ofHerpes simplex virus type 2 glycoprotein D (HSV2 gD), said HCMV gB beingfurther fused at its carboxy terminus to an internal HSV2 gD sequence,wherein the HCMV gB consists of amino acids 28-686 of the gB of HCMVstrain AD 169 wherein arginine 458 and arginine 459 are replaced byglutamine and threonine, respectively, the portion of HSV2 gD consistsof amino acids 1-52, and the internal HSV2 gD sequence consists of aminoacids PEDSALLEDPED.
 3. An isolated fusion protein comprising a HumanCytomegalovirus glycoprotein B (HCMV gB) fused at its amino terminus tothe carboxy terminus of a portion of Herpes simplex virus type 2glycoprotein D (HSV2 gD), wherein the HCMV gB consists of amino acids28-686 of the gB of HCMV strain AD 169 wherein arginine 458 and arginine459 are replaced by glutamine and threonine, respectively, and theportion of HSV2 gD consists of amino acids 1-25.
 4. An isolated fusionprotein comprising a Human Cytomegalovirus glycoprotein B (HCMV gB)fused at its amino terminus to the carboxy terminus of a portion ofHerpes simplex virus type 2 glycoprotein D (HSV2 gD), wherein the HCMVgB consists of amino acids 28-686 of the gB of HCMV strain AD 169wherein arginine 458 and arginine 459 are replaced by glutamine andthreonine, respectively, and the portion of HSV2 gD consists of aminoacids 26-52.